Machinery for stitching signatures is well known in the art. These known machines incorporate mechanisms that form staples from a coil of wire. However, there are many unsolved problems in this art that have previously precluded supplying simple reliable machinery that operates at high speeds such as 60,000 items per hour for on-line incorporation in printing and collating systems with enough versatility to operate both on signatures and webs without restriction in travel direction. A brief description of representative typical prior art patents exhibiting deficiencies corrected by this invention follows.
U.S. Pat. No. 2,869,863--Stobb, Jan. 20, 1959 and U.S. Pat. No. 2,104,852--Crafts, Jan. 4, 1938 represent the class of art that passes signatures through a set of rotating drums where staples are inserted at the line of contact between the drums. Several deficiencies exist in this class of stitching machinery. A major problem is wear and tear and corresponding complex mechanisms requiring high peak impact energy. This is caused by the requirement to eject and clench a staple almost instantaneously in a very small angle of drum rotation as the staples near the adjoining drum surfaces. In addition the staple wire must be very stiff to stand this impact and thus can be expensive and can cause cosmetic problems in the signature. Furthermore, the U-shaped staples must be inserted crosswise to the travel of paper along the line of drum contact so that both points penetrate the paper simultaneously, thus preventing the stapling action when the paper is moving in the perpendicular direction. This many times requires a mechanism in a system for changing travel direction of the signature. Also it in general prevents the on-line stitching of a travelling web before signatures are isolated, because the web must be cut and the signature travel direction changed to use this type of mechanism.
U.S. Pat. No. 1,784,590--Greene, Dec. 9, 1930 and U.S. Pat. No. 2,105,372--Pratt, Jan. 11, 1938 and U.S. Pat. No. 2,693,595--Belluche et al., Nov. 9, 1954 represent a class of stitching machines that staple creased signatures along the crease. While this is desirable in some applications these machines may lack the versatility to handle flat sheets or continuous webs. Also the latter patent is representative of the class of machines that require a separate spool of wire and corresponding staplers for each of the multiple staples to be provided in a signature. This leads to complex machinery tending to be less reliable and high cost since the wire handling and cutting equipment of the prior art is usually complex.
Also Belluche et al. represents the class of stitchers using reciprocating cycle staplers. Such staplers are intermittent and require reciprocation of heavy stapler mechanisms. Also they require attendant synchronizing apparatus in systems processing various types of paper products. The inertia of moving any such relatively heavy apparatus through start-stop cycles at each end of the operation is great, thereby cutting down on potential top reliable speed of operation, and the reliability is low and cost is high for such complex stapling equipment in this mode of operation.
The Belluche et al. apparatus also represents a class of machines which require the signature to stop in transit to receive the staples. Further typical of the piece by piece feeding approach is the U.S. Pat. No. 1,937,979--Reynolds, Dec. 5, 1933. Higher speeds can be obtained reliably by processing continuously moving paper.
U.S. Pat. No. 1,676,156--Rader, July 3, 1928 is representative of stitching machinery requiring such complex and intricate mechanisms that it is very difficult to maintain and to keep in operation reliably over long time period at high operation speeds. Such machinery is unduly expensive. Many machines of this class have extensive and complex mechanisms requiring precision alignment and interaction for forming, transporting and inserting staples, with the attendant problems of jamming and malfunction. These mechanisms are also in general not adaptable to the versatility required to form staples of various lengths for use in signatures of different thicknesses or for handling continuous webs or documents with various travel speeds or directions of travel.
The prior art is replete with complex stapler forming and clinching mechanisms. Some require complex travel paths for wire taken from rolls and complex transport and forming mechanisms. Any system complexity reduces reliability and increases critical downtime and also results in higher cost. Thus the formation of staples from a wire roll, transport of staples and clenching in the paper product is a critical part of any stitching system. In this respect, U.S. Pat. No. 223,252--Smyth, Jan. 6, 1880, uses preformed staples which are transported in part by a magnet in their transit path as shown.
It is therefore an object of this invention to correct the foregoing defects of the prior art and to provide simple non-critical, inexpensive and effective high speed on-line stapling methods and apparatus for processing either continuous webs, individual signatures and other such paper products.
Further objects, features and advantages of the invention will be found throughout the remaining description, drawings and claims.